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Biomedical subjects

N Petersen

Publications and source records attributed to N Petersen.

At least 55 records · Page 3Linked to original sources
PubMed1994

[Molecular biological screening of viruses important to transfusion medicine].

The usefulness of the direct virus detection by polymerase chain reaction (PCR) and reverse transcription/polymerase chain reaction (RT PCR) for blood donor screening was investigated, including the following viruses: cytomegalovirus (CMV), hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency type 1 virus (HIV1). Hepatitis C viraemia was detected by RT PCR in 97% of anti-HCV-positive haemophiliacs, in 48% of anti-HCV-positive hepatitis patients, in only 21% of anti-HCV-positive blood donors from North-West Germany, and not at all in 945 blood donors with elevated serum ALT. In order to compare HIV1 detection by PCR and by p24 antigen determination, we tested 34 anti-HIV1-positive AIDS patients for p24 antigen, HIV1 RNA and HIV1 provirus DNA. 97% had HIV1 provirus DNA, 35% had HIV RNA, but only 30% had p24 antigen. A multiplex PCR specific for HBV, HCV and HIV1 (RNA and DNA) was developed for the investigation of a blood donor population from Namibia, where HBV and HIV1 infections occur more frequently than in German blood donors. The prevalence of anti-HIV1 antibodies in this population was 0.6%. HIV1 RNA was never detected in the plasma of 2,569 anti-HIV1-negative donors. HIV1 provirus DNA was present in 75% of the 16 anti-HIV1-positive individuals. None of these anti-HIV1-positive blood donors was also positive for p24 antigen. CMV infections and reactivations in 130 immunocompromised heart transplant patients and in 420 healthy anti-CMV-positive blood donors were monitored using cytochemical detection of CMV early antigen, and PCR. CMV DNA was neither detected in the plasma nor in the leucocytes of any anti-CMV-positive blood donor. During the course of CMV reactivation in immunocompromised heart transplant patients, CMV DNA was always detectable first in granulocytes and afterwards in the plasma. The cytochemical demonstration of CMV early antigen was typically delayed by several days and was observed in only 11% of those blood samples which contained CMV DNA in leucocytes. The determination of CMV DNA in leucocytes proved to be the most sensitive method to detect viraemia. Thus, CMV detection in leucocytes is the method of choice for the monitoring of transplant patients. This method is also promising for blood donor screening. The sensitive routine monitoring of blood donations for virus infections by multiplex PCR is practicable. However, nucleic acid must be extracted both from the plasma and from the cellular compartments of blood in order to detect HIV and CMV provirus DNA. Lysate from EDTA blood is a suitable material for this purpose. The determination of the surrogate marker serum ALT activity is of no use in hepatitis C screening, and determination of p24 antigen is not required in HIV1 screening.

Acquired Immunodeficiency Syndrome↗
PubMed1994

[Protein A immunoadsorption treatment of patients with refractory autoimmune thrombopenia].

Eight patients with chronic immunothrombocytopenia (ITP) who had failed at least one alternative therapy were treated with extracorporeal immunoadsorption. Two of the 8 patients responded to the treatment with a stable increase in platelet counts, but both of them had to be continuously treated with corticosteroids. Side effects of the treatment with extracorporeal immunoadsorption were musculoskeletal pain, nausea, vomiting, tachycardia, purpura, fatigue, and others.

Adrenal Cortex Hormones↗
PubMed1993

H-reflexes are less depressed following muscle stretch in spastic spinal cord injured patients than in healthy subjects.

The size of the soleus H-reflex was measured after a slow (17 deg/s) passive stretch of ankle plantarflexors and compared to its control size without muscle stretch in ten neurologically healthy subjects and in six spastic spinal-cord-injured patients. Two seconds after the end of the stretch, the size of the H-reflex was reduced to about 30% of its pre-stretch size in the healthy subjects. The depression remained for 10-15 s. In the spastic, spinal-cord-injured patients, stretch caused significantly less reduction in the size of the H-reflex. The H-reflex also regained its pre-stretch size much faster than in healthy subjects. We suggest that the smaller depression of the H-reflex observed in spastic patients may be involved in the pathophysiology of spasticity.

Adult↗
PubMed1993

Variation in hemodialysis patient compliance according to demographic characteristics.

Patient noncompliance with treatment regime undermines the effectiveness of medical care, resulting in an unpredictable progression of the primary disease and a greater likelihood of complications. Hemodialysis patients are well suited for studying noncompliance because their treatment is prolonged and intensive, and medical regimens are clear cut and easily determined with objective measures. Moreover, noncompliant behavior by these patients not only endangers their life in the long run, but also results in negative effects within a day or two. Despite severe consequences, noncompliance with their medical regimen is the norm for dialysis patients rather than the exception. A large-scale study of chronic, outpatient hemodialysis patients (N = 1230 patients, response rate = 96%) treated in a variety of facility types (N = 29 facilities) was conducted to investigate prevalence and associated demographic characteristics of noncompliance with four treatment regimens--protein and potassium restrictions in the diet, medication regimen, and fluid restrictions. Few patients were noncompliant with diet regimens (9% with protein and 2% with potassium restrictions) but half were noncompliant with medication taking (50.2%) and fluid restrictions (49.5%). The prevalence of noncompliance with medication and fluid regimens was consistent with previous studies of dialysis patients but the prevalence of noncompliance with diet was much lower than that reported elsewhere. Prevalence of noncompliant patients varied between studies according to the cut-point used to establish compliance criteria, where more stringent cut-points inflated the percentage and more lenient cut-points reduced the percentage. Thus, there is a need to establish uniform criteria in order to test real differences in compliance between patient groups vs simply differences in measurement.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Task-related changes in the effect of magnetic brain stimulation on spinal neurones in man.

1. The effect of magnetic stimulation of the human motor cortex on the excitability of soleus, tibialis anterior and flexor carpi radialis motoneurones was investigated by H reflex testing in ten healthy subjects. 2. At rest, an early facilitation of the flexor capri radialis and tibialis anterior H reflexes was always seen, whereas a similar early facilitation of the soleus H reflex was seen in only two out of seven subjects. For all three motoneuronal pools the facilitation was curtailed 1-5 ms later by an inhibition which lasted for another 3-4 ms. In five subjects an inhibition without any evidence of an earlier facilitation was seen for the soleus H reflex. 3. The intensity of the magnetic stimulation was subsequently decreased so that it had no effect on the H reflex at rest. When the subject then performed a voluntary agonist contraction a facilitatory effect with an early onset and a duration of 20-25 ms was observed for all three muscles. When the subject performed a voluntary antagonist contraction an inhibition was seen for the soleus H reflex with an onset 1-3 ms later than the facilitation. This is interpreted as resulting from the excitation by the magnetic stimulus of corticospinal neurones voluntarily activated in relation to the given motor task. 4. The initial part of the facilitation was significantly smaller during co-contraction of both agonists and antagonists than during isolated agonist contraction. 5. Whereas the early part of the facilitation always occurred during plantarflexion when the H reflex was conditioned by magnetic stimulation, this was never the case when it was conditioned by electrical stimulation of the cortex with the stimulus regimes used in these experiments. 6. It is suggested that the early part of the facilitation observed during agonist contraction is caused by activation of cortico-motoneuronal cells projecting to the agonist motoneuronal pool and that the inhibition observed during antagonist contraction is caused by activation of corticospinal cells projecting both to the antagonist motoneuronal pool and Ia inhibitory interneurones to the agonist motoneuronal pool. The smaller size of the earliest part of the facilitation observed during co-contraction in relation to agonist contraction suggests a different cortical control of the two tasks.

Adult↗
PubMed1993

Dominating role of an unusual magnetotactic bacterium in the microaerobic zone of a freshwater sediment.

A combination of polymerase chain reaction-assisted rRNA sequence retrieval and fluorescent oligonucleotide probing was used to identify in situ a hitherto unculturable, big, magnetotactic, rod-shaped organism in freshwater sediment samples collected from Lake Chiemsee. Tentatively named "Magnetobacterium bavaricum," this bacterium is evolutionarily distant from all other phylogenetically characterized magnetotactic bacteria and contains unusually high numbers of magnetosomes (up to 1,000 magnetosomes per cell). The spatial distribution in the sediment was studied, and up to 7 x 10 active cells per cm were found in the microaerobic zone. Considering its average volume (25.8 +/- 4.1 mum) and relative abundance (0.64 +/- 0.17%), "M. bavaricum" may account for approximately 30% of the microbial biovolume and may therefore be a dominant fraction of the microbial community in this layer. Its microhabitat and its high content of sulfur globules and magnetosomes suggest that this organism has an iron-dependent way of energy conservation which depends on balanced gradients of oxygen and sulfide.

Journal Article↗
PubMed1991

The impact of economic considerations on clinical decisionmaking: the case of thrombolytic therapy.

This study examines the intravenous use of two thrombolytic agents [streptokinase (SK) and tissue plasminogen activator (tPA)] in the acute phase of myocardial infarction (MI). These two agents have very different costs and offer an excellent opportunity to study both the impact of economic factors on clinical decisionmaking and the potential for cost savings by limiting the use of expensive new therapeutic agents. A nationwide survey of the 5,792 acute care general hospitals listed in the American Hospital Association's 1988 data file was responded to by 2,651 hospitals (46%) and revealed that 2,384 of these responding hospitals (90%) were using thrombolytic therapy. For 2,200 of these 2,384 hospitals (92%), the respondent was a physician who primarily used one of the two drugs. Eight hundred eighty-six of these 2,200 physicians (40%) primarily used SK while 1,314 (60%) primarily used tPA. SK users were more concentrated in federal public hospitals (69% used SK) than in nonfederal public hospitals (47% used SK), and were least concentrated in private hospitals (36% used SK). There was no difference between the rate of SK vs tPA use in investor-owned and not-for-profit private hospitals. SK users most often (62%) cited various economic factors as the reason for their choice. The users of tPA primarily (73%) cited clinical preferability as the reason for their choice even though trials are still ongoing to see which drug is preferable. Several multivariate analyses shed light upon the association between choice of thrombolytic agent and various additional physician and hospital characteristics. These data clearly indicate that while new therapies are rapidly implemented by the medical community, considerations of cost have a substantial impact upon the pattern of implementation and reflect a desire to implement cost savings in the use of new drugs.

Data Collection↗
PubMed1989

An uncontrolled study of cognitive therapy for morbid jealousy.

Thirteen patients presenting with morbid jealousy were treated using a cognitive approach adapted from Beck's cognitive therapy for depression. Cognitions in morbid jealousy showed the characteristics of automatic thoughts as described by Beck, and were based on faulty assumptions derived from interpretations of past experiences. The cognitive treatment directed mainly at the faulty assumptions resulted in improvements in ten patients and no change in one; two patients dropped out of treatment. The results are considered encouraging.

Adult↗
PubMed1985

Effect of physical training on glucose transporters in fat cell fractions.

Physical training increases maximally insulin-stimulated glucose assimilation and 3-O-methylglucose transport in epididymal fat cells. In the present report, glucose-inhibitable cytochalasin B binding in subcellular fractions of epididymal adipocytes was measured to assess changes in number of glucose transporters induced by training. Groups of rats trained by swimming were compared to control groups of the same age, matched with respect to body weight by restricted feeding. It was found that in trained rats the number of glucose transporters in the low density microsome fractions from non-insulin-stimulated fat cells was larger than in untrained rats. In both groups of rats, insulin stimulation of adipocytes decreased the number of glucose transporters in low-density microsomes by about 60% and increased the number of glucose transporters in the plasma membrane fractions. The number of glucose transporters in the plasma membrane fractions from maximally insulin-stimulated fat cells was larger in trained rats than in control rats. [U-14C]Glucose incorporation into lipids varied in proportion to plasma membrane cytochalasin B binding per cell under all conditions tested. The results explain the enhancing effect of training on insulin responsiveness transport of hexose in fat cells.

5'-Nucleotidase↗
PubMed1977

[Malignant mediastinal lymphoblastic lymphoma with t-cell ALL (author's transl)].

29 cases of T-cell derived lymphoblastic lymphoma and T-ALL have been analyzed. There is a striking prevalence of the male sex. In the peripheral blood we often find initially an excessive number of white blood cells combined with normal values for the other constituents in about half of the patients; This may be an expression for the rapid occurrence of leukaemia in T-cell lymphosarcoma. In addition to systemic ALL-therapy we performed X-ray irradiation of the mediastinum in 8 of our patients. This yielded to significantly longer first complete remissions. All patients with T-cell LSA/ALL with or without mediastinal mass should be treated in this manner. Cytochemically a strong focal acid phosphatase reaction was found to be acharacteristic of these cells. It has proved to be a screening method for this disease. The cells are T-cell derived and their pattern of surface markers is similar to that found in fetal thymocytes.

Acid Phosphatase↗
PubMed1976

Ribosomal subunit entry into polysomes in yeast.

The kinetics of entry of newly synthesized 40 S and 60 S ribosomal subunits into yeast polysomes is described. The entry times for 40 S and 60 S subunits were found to be 3 and 8 min, respectively. The kinetics of entry of 40 S subunits into large polysomes is found to be different from the kinetics of entry of 60 S subunits into large polysomes.

Adenine↗
PubMed1976

Lymphoblastic lymphoma of convoluted or acid phosphatase type-a tumor of T precursor cells.

Five lymphatic neoplasms with strong focal acid phosphatase reactivity were selected from a group of acute lymphocytic leukemias and lymphoblastic lymphomas. All five cases showed an anterior mediastinal mass and exhibited identical morphology. This type of lymphoma has been described by Lukes under the term "malignant lymphoma of convoluted lymphocytes". Analysis of surface membrane receptors revealed that the tumor cells lacked surface immunoglobulin and receptors for Fc-fragment, but possessed receptors for complement (C3), untreated SRBC (ES) and SRBC treated with neuraminidase (ESN). By applying a mixed rosette assay using nucleated chicken erythrocytes coated with antibodies and C3, and denucleated ESN, it was found that a considerable number of tumor cells in all five cases formed mixed rosettes, i.e. that they bore the C3 receptor characteristic of B cells and simultaneously the E receptor characteristic of T cells. Thus the tumor cells resembled immature thymocytes of 10-15 weeks' gestation, which also show focal acid phosphatase reactivity and simultaneous expression of C3 and E receptors.

Acid Phosphatase↗